With the progress of the digital technology in electric devices in recent years, demands for non-volatile memory devices with a large capacity have been increasing for storing data such as music, images, information, and so on. As a measure to meet such demands, a non-volatile memory device (hereinafter referred to as ReRAM) has been attracting attention, which includes, as a memory element, a variable resistance layer which has a resistance value that changes in response to a provided electric pulse and holds the state. This is because the ReRAM has characteristics that the structure as a memory element is comparatively simple and suitable for increasing density; and that it is easy to ensure consistency with conventional semiconductor processes. With such a ReRAM, a material which can stably cause a designed change in a resistance value with an excellent reproducibility even when a memory element is miniaturized, and establishment of a manufacturing process of the memory element are required. Research and development for such a material and a manufacturing process are actively conducted.
A memory device having a stacking structure is proposed as a structure allowing further dense integration in the ReRAM. FIG. 14 shows a cross-sectional diagram of a non-volatile memory device according to conventional examples disclosed by Patent Literatures 1, 2, and 3. The memory device includes: a stacked body in which a plurality of conductive layers 1413 and a plurality of interlayer insulating films 1417 are alternately stacked; a variable resistance layer 1414 formed to perpendicularly intersects the stacked body and to have a cylindrical shape; and a pillar electrode 1412 formed to be in contact with an inner side surface of the variable resistance layer 1414.
In addition, FIG. 15 shows a cross-sectional diagram of a non-volatile memory device according to the conventional example disclosed by Patent Literature 4. The memory device includes: an interlayer insulating film 1517 disposed parallel to a substrate 1511; conductive layers 1513 each disposed parallel to the substrate 1511 and shaped into a strip; a pillar electrodes 1512 each intersecting perpendicularly to the substrate 1511; and variable resistance layers 1514 disposed between the pillar electrodes 1512 and the conductive layers 1513.
The variable resistance layers 1514 are formed by oxidizing an overlap region in each of the conductive layers 1513. In the overlap region, the conductive layer 1513 intersects a corresponding one of the pillar electrodes 1512.